Hipdysplacia

The
following article is duplicated from the Dutch Kennel Club’s brochure,
department GGW (the former WK Hirschfeld Stichting).

Hipdysplasia
Hipdysplasia is a development disorder from the hip-joints, due to hereditary
and environmental influences. Some dog are severely bothered by this. There are
also dogs with more or less severe deformations of the hip-joints, who don’t
seem to be bothered by this at all. The judgement of the gait of these dogs
gives insufficient information about the condition of the hip-joints.
More information can be gathered with the help of x-rays.

The
rating panel
One of the functions of the HD-panel from the Dutch Kennelclub, department
Health, Behaviour and Wellbeing (GGW), is the rating of x-rays of the hip-joints
from dogs. The x-rays, the so called HD x-rays can be made by every veterinarian
which has a contract with the GGW. HD x-rays are all rated together by an in
construction changing panel of three qualified judges. The objective rating of
the x-rays, which is so important for CHD prevention, is secured as good as
possible this way. The rating of HD x-rays has the purpose to give information
to the breeders and breedclubs who use information of hypdisplasia in their
breeding selection programs. X-rays which come in at the GGW department will be
rated in the week after delivery. After the GGW received the rating costs, the
results are send, unless the x-rays did not meet with the technical demands.

HD
x-rays
For a good rating of the hip-joints, two x-rays are needed from the dog, laying
on his back:
- one x-ray with stretched rear paws (position I), and
- one x-ray with the rear paws bend forward and spread (position II). In both
positions the dog has to lay exactly straight. For the reliability of the
ratings, high demands are needed in quality and documentation (identification)
from these x-rays. If these demands are not reached, the veterinarian who made
the x-rays will be informed, with a note about what was not correct and a
request to make new x-rays. Such a request is send immediately after the rating
of the x-rays and is at the latest within two weeks after GGW received the x-ray,
at the veterinarian’s. He should contact the owner of the dog to make a
appointment for new x-rays. The rating of these new x-rays will not be charged.

Certificate-Hipdysplasia-Research
On the certificate-Hipdysplasia-Research you will find the definitive rating,
the F.C.I.-rating, and several indications which explain the definitive rating.
The rating HD- (HD A, = negative) means that the dog is clear of hipdysplasia,
which does however not mean that the dog is no “carrier” of the condition.
HD tc (HD B, = transitional changes) means that some slight changes have been
found on the x-rays, which should be accounted for by CHD, but in breeding
programs have no direct meaning. The rating HD ± (HD C, = slightly positive) or
HD + (HD D, = positive) mean that changes, which do fit the CHD condition, are
found in the dog.
When the hip joints are severely deformed, the rating HD++ (HD E, = positive
optima forma) will be given.

F.C.I.-rating
The F.C.I.-rating is a translation of the HD-rating to international values,
which makes it possible to compare HD-results from other F.C.I. countries.

The
rating of the different parts
At the rating of HD x-rays, they check the form of the hipsocket and femurhead,
the depth of the socket, the closure of the femurhead in the socket and the
presence of arthritis on the edges of the hip-joints. Information on the depth
of the socket and the closure of the femurhead in the socket is gathered from
the so called “Norbergwaarde” (=Norbergvalue), which is measured on the
x-ray in position I. The Norbergvalue from the left and the right hip are added
and together they give the on the certificate mentioned “sum Norbergvalue”.
From a normal hip-joint the Norbergvalue is at least 15, the sum Norbergvalues
from both hips are therefore at least 30. Dogs with a too low Norbergvalue have
either undeep sockets and/or a bad closure of the joint-parts. These dogs will
get a less good HD-rating. A normal or even high Norbergvalue does not
necessarily mean that the dog has good hip-joints. A combination of deep sockets
and incongruention of the joint closure (not everywhere the same closure) or
insufficient closure of the joint-parts, can even at a high Norbergvalue, lead
to a (slight)-HD-positive rating. On the certificate, this is marked by
“insufficient” or “bad” closure. Information about the depth of the
socket is also gathered by judging how the centre of the socket is placed
compared to the upper edge of the socket. Next to the Norbergvalue, the depth of
the socket and the closure of the joint-parts, the ratings are also influenced
by “bone-deformation”. There is a direct link between the grade of the
bone-deformation and the rating: very slight bone-deformation (1) will lead to
an HD tc (HD B), slight (2) bone-deformation will lead to an HD ± (HD C) and
severe (3) bone-deformation will lead to an HD + (HD D) rating. The note “form
changes” usually means a more or less obvious flattening from the edge of the
socket. The presence of this is noted, but if this is the only note about the
joints, this does not have a sufficient meaning in the end result.

HD-rating
All information together will lead to the definitive rating, where the
less good part has the most important influence. One certain HD-rating can be
made from only the depth of the sockets, the closure of the joint-parts, the
presence of arthritis, or from a combination of two or all three parts, and this
is mentioned on the certificate.

Repeating
the HD-researchEvery
owner can have a new HD-research done after a minimum of 1 year. The
score, which will come from this, will replace the earlier score from the moment
the new rating is done. Repeating the research can only positively influence the
result if the dog has been research at the age of 1 or 1.5 years of age, and
where a slight positive rating had been given because of bad closure, with or
without that low Norbergvalue, while there was no bone-deformation.

The
Norbergvalue
They take the centre of both femurheads (1) and these centres are connected with
a line. In both hip-joints a line is drawn from through the centre to the edges
of the socket (2). The angles (3) that both lines make with each other, minus
90, will give the Norbergvalue for that particular hip-joint. The Norbergvalue
of that left and right joints added together, will give the “sum Norbergvalue”
which is reported on the certificate.

Your
dog and CHD
Owners of dogs that have been officially x-rayed often ask the vet that made the
x-rays for his or hers opinion on the state of the hip-joints. If the first
impression of the vet is milder than the definitive score, the dog’s owner is
often disappointed. The HD-panel advises veterinarians not to make any remarks
on the condition of the hip-joints. From dogs which are not clear of
Hipdysplasia, but who do not show any signs from the outside, it is impossible
to predict if they will have problems sooner or later. Also when severe
deformations are found, this does not mean that the dog will have
problems. It is wise to see to it that the dog will not be too heavy and also
that otherwise stressing the hip-joints is avoided. This does depend on the
demands the owner does have on his dog as pet or workingdog. In case of doubt,
you can always consult with your vet.

HD
and breeding
The CHD-rating only gives information about the hip-joints of the individual
dog. Information about the CHD-rating from parents, littermates and offspring
will contribute to a more accurate impression about the breeding-quality of that
individual dog. It is very important that breedclubs have access to all results
and that all HD x-rays that are made also are send to official rating by the
HD-panel, even if the veterinarian sees obvious deformations in the hip-joints.
Best is to only breed with HD – (HD A) dogs, because chances of CHD in the
offspring are reduced to a minimum that way. With breeds that only have a
limited population and breeds in which CHD often occurs, this is unfortunately
not possible. Within the breed-club, breeders should consult with the
Kennelclub, GGW department, about what is necessary and possible in the name of
CHD prevention and what is accepted in the name of breeding.

If
there are any questions after reading the above, you can contact, preferably by
mail:
Raad van Beheer, afdeling GGW, Postbus 75901, 1070 AXAmsterdam
Telephone/Fax +31 (0)20-6794462